


Caesium

by 7PercentSolution



Series: Periodic Tales [6]
Category: Sherlock (TV)
Genre: Angst, Case Fic, Chemistry, Gen, Kidlock, brotherly bickering
Language: English
Status: Completed
Published: 2016-07-17
Updated: 2016-07-17
Packaged: 2018-07-24 13:58:07
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 3
Words: 6,669
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7511005
Author URL: https://archiveofourown.org/users/7PercentSolution/pseuds/7PercentSolution
Summary: <blockquote class="userstuff">
              <p>Caesium<br/>Cs   55    132.9049</p><p>An alkali metal which is soft, silvery-gold in colour with a melting point of 28 °C (82 °F), which makes it one of only five elemental metals that are liquid at (or near) room temperature. It is highly reactive, igniting spontaneously in air, and it reacts explosively with water even at low temperatures. When it burns, caesium emits a bright clear blue colour.</p>
            </blockquote>





	1. Chapter 1

John was sitting at the table, Sherlock was in his chair. It was pouring rain outside, so both of the men were working on their respective blogs.

"Sherlock."

No reply, so John tried again.

"Sherlock, you have a fan."

"Hmmm?"

The consulting detective did not look up; but kept typing in his furious pace. It was just one of the things that Sherlock did so much better than John, who had never managed to use more than four of his ten fingers when typing. John tried not to be jealous of his flatmate's manual dexterity.

"She – or maybe he- not easy to tell from the tumblr name- just posted a question on my blog. Wants to know what colour your eyes are."

John watched the furrows appear on either side of Sherlock's brows.

"Why?"

"Apparently, there is some debate about it."

The brunet snorted. "My passport says 'blue'."

Now it was John's turn to snort in derision. "No, Sherlock.  _My_ eyes are blue. So are Mycroft's. Yours are something else. Grey? Silver? Green? I don't know…you tell me. The person posting on my blog says your eye colour changes like some sort of chameleon- or an alien."

Sherlock finally looked up from his own laptop and scowled. Right now John would call the colour of his flatmate's eyes 'stormy'.

"You realise that eye colour is …a rather complicated subject? The presence of certain proteins in the melanocyte cells are the basic ingredients of everyone's eye colour, and the distribution of it in each iris is unique. Everyone's eyes have a different mix of pigments in different places in the iris, and each eye is different. I have a spot of brown in my right eye near the pupil, but it's not there in my left eye. Iris recognition systems are based on those facts. "

John looked down at his keyboard, as if considering how to translate that into a simple answer.

Sherlock sighed. "John, just tell her the science. There is no such thing as blue or green pigmentation in an eye. That's the effect of the scattering of light through the two layers of iris cells- the same way the sky is thought to be blue, when it isn't, actually  _blue_.

"So, what do you suggest I say in my reply to her question-'none of the above'?"

"My mother once used a French term for the colour of my eyes –  _glasz_. That's not spelled like glass by the way; it has a final zed not a second s; it's a Breton word and relates to the colour of the sea. Personally, I prefer to use the chemistry definition."

Now John looked even more perplexed.

"In 1860, a German chemist Robert Bunsen – yes, the Bunsen burner is named after him- and a physicist colleague, Gustav Kirchhoff, used a spectroscope for the first time to discover a new element. It produced two blue lines that no one had ever seen before; they called it  _caesium_  after the Latin Word for 'heavenly blue'.

Smirking, he returned to typing on his laptop.

John began to type.

oOo

Just under four hours after receiving a phone call from the Royal Bethlem Hospital, Mycroft Holmes walked into the reception area of the Mount Sinai Rehabilitation clinic. His journey had taken him from Oxford to Paddington Station, then across London to Victoria Station and then out by train again to Bromley South, then finally a taxi to the clinic He asked at the front desk for Doctor Esther Cohen.

"Oh, yes- you must be Mr Holmes. Please take a seat while I page her."

He looked around the reception area, with its comfortable seating and potted plants. The three storey modern building was in a small clearing, surrounded by trees and ringed with flower beds. Light, clean and airy, the large plate glass windows let sunshine in. It didn't feel like a hospital.

He watched as a young couple with a small child gathered around an elderly woman sitting in the garden enjoying the afternoon sunshine.  _Happy family; doting grandmother._ From the way she was sitting on the bench, he decided she was recovering from either a broken hip or a hip replacement- hard to tell at this distance. For some reason, it made him think about his grandmother, Sophia.

"Hello, Mycroft."

"Doctor Cohen." He stood and shook hands with the small woman. Her eyes were sparkling and she smiled broadly.

"How is he?"

"Recovering. I sedated him at the hospital, so the move wouldn't distress him. He's still asleep."

For a moment, neither of them spoke, as if unsure where to begin. Another patient came by, this one in a wheel-chair, being pushed by an attendant.

"The patients here seem to be ….rather older than I expected."

Esther stifled a giggle. "Yes, well- that's because it's a private geriatric rehabilitation unit, run by my uncle: forty beds for the wealthy Jewish widows of south London. I think it was growing up with this in the family that made me want to do paediatrics, to be honest. But, family is useful in times of need, and Uncle Harold was willing to do me a favour on short notice. Your brother was admitted under the name of Shirley Cohen. I doubt your father will be able to figure it out. I managed to get Sherlock moved before Bethlem hospital was able to get in touch with him in the Far East. It's all legal, by the way. In the absence of a parent, another adult family member is able to issue instructions, so the hospital discharge papers are all in order. I got the Emergency Department to tell Doctor Molhotra that the family has decided that Sherlock won't be coming back to the King's Court Clinic, given the circumstances. So, we have a little time before deciding what to do next."

"I want to thank you, Doctor Cohen, for finding my brother."

She shook her head. "I didn't  _find_ him; he found me. We have to chalk this one up to coincidence and serendipity. The clinic he was at- Kings Court Clinic in Orpington- brings its emergency cases to Bethlem, and I just happened to be the duty doctor this morning."

"However it happened, it means he's safe now. Can I see him, please?"

She smiled again. "Of course."

On the second floor, at the end of the corridor, she stopped in front of a closed door. "Before we go in, I should tell you what I've been able to get from the admission team about what happened. Sherlock was being treated for depression, and he horded the drugs until he could take an overdose. Ten's a little young for purposive suicide, but there is no doubt that he knew what he was doing. Apparently, last month a teenager from the same clinic overdosed and my guess is that this was a copy-cat. According to the ED doctor the clinic said that Sherlock's not spoken a word since arriving there in January. They had him on lithium for a while, but that's been tapered off, and anti-depressants introduced instead." She stopped for a moment.

Mycroft caught the hesitation. "What is it you are finding hard to tell me, Doctor Cohen?"

She looked away for a moment, then turned her eyes back to the tall young man. "The clinic used a rather old fashioned treatment to try to break him out of a near catatonic state, and they've kept it up, too, according to what my ED colleague got out of the clinic. Have you ever heard of ECT?"

Mycroft shook his head, the initials didn't mean anything to him.

"Electroconvulsive Therapy. The patient is anaesthetised, given a muscle relaxant injection and then a brief electrical stimulus is given to the brain, using electrodes put onto the temple. The electrical impulse lasts about four seconds. It induces a seizure."

"Why?" Mycroft did not disguise his surprise.

"That's a good question, wish I had a simple answer. There are some who say it affects the way neurotransmitters work in the brain. It's used to treat severe depressions, when anti-depressants aren't working."

Mycroft picked up on her discomfort. "You don't think the treatment was warranted?"

She shrugged. "I don't  _know_ , do I? I have not examined your brother, not tried to speak with him or identified what is the nature of his problem or the state of his mind. I can't say for sure. If he hasn't said a word for five months, and not engaged with any therapy, then perhaps the doctors felt there was no alternative. But, for a child on the autism spectrum, I …" She hesitated again.

"It's just that there are side effects of ECT- memory loss and disorientation being the most common. That would be bad enough for a neuro-typical child. For someone who needs familiar surroundings, for whom communication is hard and social engagement difficult- well, it could drive that patient even further into themselves. So, I guess what I am saying is that he may not be the brother you knew. I can't even guarantee that he will recognise you."

_Father would know this. He would have chosen this therapy on purpose._  Mycroft looked down at the doctor. "If that happened, if the treatment only exacerbated the autistic tendencies, would that justify indefinite institutionalisation?"

She was surprised by the young man's dispassionate assessment. "Yes, I suppose it would."

Mycroft's gave her a steely look. "Then it is safe to say that my father knew this and agreed to the treatment with the express intention of doing just that."

She looked horrified. "How could a parent do that?"

"You have not met my father, Doctor Cohen. Now, can I see my brother, please?"

She opened the door and they went in. There was a heart monitor beeping quietly beside the single bed in the room. Sherlock's face on the pillow was half obscured by long dark curls.  _He hasn't had a haircut since January._  Mycroft just looked at him. In repose, the lines were soft, but he could see that his brother had lost weight from the prominence of his cheekbones. His eyes were a bit sunken, the sockets dark, almost bruised.

Doctor Cohen was watching the monitor, and murmured "a good rhythm; no side effects then from the overdose. He should wake up in a couple of hours."

Mycroft smirked. "He's awake now, and listening to us. He heard our conversation outside, too. He knows it's me, but he's not too sure about you."

He looked down at the hospital bed and fumbled for a latch. Esther released it for him, so the bars could drop on his side. Mycroft then leaned down so his eyes were level with the edge of the pillow.

"She's OK, I promise. You're safe here."

There was no movement at all.

"Open your eyes, Sherlock; this isn't a dream. I've finally found you."

The dark lashes fluttered, and Mycroft found himself looking into those impossibly blue eyes. He smiled. Sherlock just looked at his brother, really  _looked_.

Doctor Cohen held her breath.

"What took you so long, Myc?" The voice was a bit croaky, as If rusty from lack of use. But the words were real, and they came from the mouth of a boy who had not spoken in five months. A thin arm came out from under the sheet, and reached up, fingers splayed. Mycroft extended each of his longer fingers and then touched them to his brother's.

Esther Cohen could only think  _he's got such beautiful eyes._


	2. Chapter 2

**Summary for the Chapter:**

> Alkali metals are highly reactive, and cesium, being one of the heaviest alkali metals, is one of the most reactive. It is highly explosive when it comes into contact with both air and water. This contact generates hydrogen gas that is heated by thermal energy that is released at the same time, which then causes ignition of the gas and a violent explosion ensues. Because cesium is so reactive, even ice can trigger an explosion.

"Mycroft, the chemistry doesn't  _lie_. People do, and politicians are people- or at least they were the last time I checked. Are you suggesting that the House of Commons is now stocked with aliens who are somehow congenitally unable to lie? How did you let this happen?"

John tried to hide his smirk. When Sherlock unleashed the sarcasm, the flat became a battlefield. And no one provoked sarcasm more than the minor official in the British Government who was now gazing at his brother looking like he had just sucked on a lemon.

The two Holmes brothers were debating-  _Verbal_   _fist_   _fighting? Vocal violence? Ballistic banter?_  John tried to find a less civilised word than debating, because the exchanges were getting increasingly heated and volatile.

"Really, Sherlock. Must you resort to …schoolboy taunts? Surely even a self-confessed sociopath is able to appreciate that when people panic, it is a problem." This was said with some heat.  _Careful, Mycroft, or that 'Ice Man' image is going to melt_. John settled back to watch the fencing match, with barb and counter-thrust designed to draw blood.

At issue was the idea being put about in the newspapers that Chechen terrorists had stolen a significant quantity of caesium 137, and that London might be a target for a so-called 'dirty bomb'. Sherlock was dismissive. "Yes, of course it's a radioactive isotope, and it has a relatively long half-life of 30 years so if there were to be a significant exposure over a long period of time, it would be lethal for those in the immediate vicinity. But most of those would be at greater risk from the conventional blast damage."

Mycroft sighed. "Oh, do grow up! You are missing the point, Sherlock. It isn't about what is actually done; it's what uninformed people think it can do that matters. The mass panic and hysteria would be what the terrorists were trying to achieve. Even the word 'caesium' sounds scary, especially when the Sun headline writers get to work on it."

Sherlock snorted. "John, explain to my ignorant brother just how common caesium 137 is."

The doctor looked startled. "Uh…why would I know that, Sherlock? We're not all blessed with a mind palace stuffed with chemistry trivia."

Sherlock looked offended. "I am surrounded by idiots, present company included." He shook his head in frustration. "Caesium 137 is a commonly used gamma source, found in virtually every hospital in the country. It's used to calibrate the radiography equipment to treat cancer. It's considered so safe that it is used to irradiate foodstuffs to kill germs and suppress sprouting of wheat-based products. After treatment, there is no radiation or residual poisonous material. It's as safe as houses. In fact, probably more so- It's commonly used to check for cracks in industrial pipelines. If you want to really wreak havoc then your common or garden variety terrorists are going to need something other than caesium."

Sherlock waved his hand dismissively, "Even the Chechens know this. The two attempts they've had so far with a bomb involving caesium were in 1995 in Izmayolvsky Park in Moscow, and then again in Chechnya in 1998. Neither of them was actually detonated because if they had been everyone would have realised it was just a damp squib- both were just PR stunts."

The consulting detective glowered at his brother. "It's spooky to idiots because caesium 137 glows blue in the dark, like some bad horror film prop. It's not a weapon of mass destruction, Mycroft. Maybe, if the authorities mishandle it, it might be a weapon of mass  _disruption_ , but that would primarily be because of the panic that people like you did little to stop. The actual impact on civilian casualties from a conventional bomb is much greater."

"Unfortunately for the rest of the world, Sherlock, we are not blessed with your grasp of the chemical elements. If we were, then there would be far less scare-mongering. But until such time – and I do think we are eons away from that blessed day- then I have to deal with the real world and its shaky grasp of anything that has the adjective 'radioactive' in front of it- be it plutonium, uranium or caesium." With that, Mycroft stood up collected his umbrella and went out to do battle with those who did not know what caesium was- let alone one of its radioactive isotopes.

oOo

"You're wanted in the Master's Office, Holmes. Best be quick about it, too."

Mycroft had been expecting it for some days, after he'd estimated just how long it would take for his father to get back from the Far East, to investigate what happened at the Kings Court Clinic and to track down to paperwork regarding Sherlock's release from Bethlem Royal Hospital. So, when the Porter knocked on the Master's office door and opened it, Mycroft knew who he was going to find on the other side.

Sir Anthony Kenny was seated at his desk. But standing at the window with his back to the room was the tall commanding figure of his father, Richard Holmes.

The Master gave him a slightly strained smile. "I am sorry to have interrupted your revision seminar with Doctor Simmonds, but your father needs to speak with you urgently." He stood up and made his way around the desk. "He's also asked for privacy, so I have offered him the use of my office. I'm off to give a lecture for the next hour." As he passed, he gave the young man a concerned look, but said nothing more before leaving the room and shutting the door quietly behind him.

Mycroft waited, his hands resting on the back of the chair that was in front of the desk.

"Where is he?" The three words were delivered in a tone that spoke of a rage scarcely held in check. Mycroft could see that the back of his father's neck was flushed, beneath the man's reddish-brown hair. He had not even turned away from the window to look at his elder son.

Mycroft's reply was cool and calm. "Who?"

"Don't play the innocent, Mycroft; it doesn't suit you. Where did you put him?"

"The location doesn't actually matter, father."

That reply made the stern figure turn away from the window, to look the young man in the eye. "What are you playing at, Mycroft?"

The eighteen year old did not acknowledge his father's withering gaze. He did not rise to the bait by trying to argue that he was not  _playing_  at anything. He stayed silent, waiting.

"Sit down." The command was almost growled.

"I prefer to stand, sir."

The answer was courteous. Mycroft would not give his father any additional cause for anger. He knew that he'd done enough, simply by finding Sherlock and removing him from his father's direct control.

However, his calmness seemed to infuriate the older man, who left the window and came to stand closer to his elder son. In the five months since his mother died, Mycroft had grown almost two inches in height. His father was no longer looking down at a child, but at a self-possessed young man, who didn't seem intimidated by the older man's height and bulk.

Richard Holmes' eyes were incandescent. "Sherlock is not your responsibility. He is mine. You will tell me exactly where he is and then you will cease to interfere with what I decide is best for him."

Mycroft kept himself utterly still. He did not give any outward indication of his nerves. His answer was calm and simple. "No."

He saw his father's pupils dilate, his face contort, but the younger man did not flinch or try to dodge the slap that came. He had expected the explosion of rage, took it, and stood his ground. Then he calmly asked, "Why do you think that physical violence will make me more likely to tell you anything?"

If it had been sarcastically said, then perhaps it would have sparked another explosion. But, because his son's question was as calmly asked as if he had been enquiring about the weather, Richard Holmes was taken aback.

Subtly, something changed in their relationship. The older man was thrown off balance. This was not Mycroft, the obedient son and heir who had done everything his parents had ever asked of him, with style and grace. This was not the genius who had dazzled his peers, delighted his elders and made a point of attracting the attention of those who saw his potential.

"What's he done to you, Mycroft? Did he come begging for help from you? Made you feel guilty somehow, made you think that you owe him something? You don't. Whatever he is saying, he's trying to manipulate you, the same way he did your mother. Caring is not an advantage, Mycroft,  _he_  isn't worth it. You have more important things to do than look after someone who can't look after himself. He'll never live an independent life; he needs the care of professionals who can deal with his particular kind of mental defect."

Mycroft looked curiously at his father. "And why do you think that argument has any more bearing now than it did when you said it to me at Easter?"

The ice cold tone must have startled his father, because he stepped back to look at his son, as if he'd never seen him before.

Richard tried again. "You are my son; you will obey me in this."

That made Mycroft tilt his head curiously. "or…what?"

At that moment, he watched realisation creep into his father's eyes. And then reassessment, followed by a kind of grudging recognition.

Mycroft nodded. "Yes, father, you taught me well. You always said don't fight battles you can't win."

That made his father scowl, "What makes you think you can  _win_  in this case?"

Mycroft's answer was almost instantaneous. "Because you have more to lose than I do if this becomes public. Neither of us wants this to go to court. But, I have the means to do so, should it become necessary. And I have the evidence I need, too. Sherlock tried to kill himself because you abandoned him. You won't win. And public exposure would be embarrassing for you in a way that it wouldn't be for me."

His father took a few strides away from him, back toward the window, and a chance to think without having to face his son's scrutiny.

When the older man turned back around, he was the one that was now curious. "Where is this headed?"

"This?"

"Well, what would you call this-a stand-off, an impasse?"

"Perhaps it would be best to think of it as …a negotiation."

There was the tiniest of smirks on Richard Holmes' lips. "Then what is on offer?"

Mycroft had thought long and hard about what was feasible. He knew that this was perhaps the most important conversation of his life so far, and he wanted it to go right, for both his sake and Sherlock's.  _Don't rush things. Let him come to it slowly._

"To start with, I want legal guardianship of Sherlock. I've drawn up the papers, all you have to do is sign and he is no longer your problem. You can be free of him, as you wanted to be, when you confined him at Kings Court. In exchange, I will withdraw the idea of court action. It's really just a formality- and it will be kept strictly private, confidential between the two of us."

The taller man nodded curtly. "And what else, because if that were all you wanted then we wouldn't be having this conversation except via lawyers. So, out with it."

Mycroft anticipated anger, but his father was being more subtle now. Probing and testing what actually was on the agenda.

"I sit my first year exams in two weeks' time, and then I'm free until October. I want to spend the summer at the estate with Sherlock, without you in residence."

Richard snorted in derision. "Why on earth would you want to do that? Leave the boy in an institution, for God's sake. You're supposed to be spending the summer on the internship at the House of Commons, or have you forgotten your promise to Sir Charles?"

"The machine of government will not grind to a halt because one intern fails to turn up. I've recommended one of the other boys on my course; he will suit Sir Charles' ambitions much better. I want Sherlock back in familiar surroundings with a face that he trusts. At the moment, that's me and no one else. He needs to get out of a place that assumes the worst of him."

"It's a waste of bloody time, Mycroft. He'll be a millstone around your neck. He'll drag you down, suck the life out of you. Instead of being…all that you could be, you'll waste energy trying to fix him. You're already compromising your own interests by turning down the internship; it's just the first step on that slippery slope. Don't do it. He's broken. Always was, always will be…a mistake. You think you're being noble and doing the right thing, but, believe me, you will regret this decision for the rest of your life."

Mycroft was unmoved and unmoveable. He waited, watching his father pace from the window to the side of the master's desk, and then back again.

"No, I can't let you do this. This isn't supposed to be how it turns out. You were all I ever wanted, all I hoped for in a son. You've never disappointed me. When I let her waste her life on Sherlock, she let me have you. That was the bargain we made."

"You didn't ask me for  _my_  opinion about that idea, Father. I can't accept it. Since Mummy died, I've learned a lot about you, and not one bit of it makes me want to agree to your arrangement."

A hint of desperation crept into his father's eyes. "He'll break you the way that he broke your mother. Damn it, Mycroft- how can you do this to me? You're all I have left now!"

"No, father, you have another son, as I have a younger brother. And, unlike you, I am not able or willing to forget that."

Mycroft looked at his father, feeling as if a great chasm had opened up between them. He was seeing the human being there rather than his father, for the first time in his life. And he didn't like what he saw. The father he had always looked up to and respected was not there. In his place was a jealous needy man prepared to reject one son and to use guilt to coerce another one to go along with his plans.

He watched as the fire, the anger went out of his father's eyes, to be replaced by the toxic fallout of disappointment. The confrontation he'd been dreading for days was over. Odd, the explosion seemed to have blown out the flame of his own emotions; he looked coldly at the man in front of him and saw him for what he was- just a man.


	3. Chapter 3

**Summary for the Chapter:**

> Caesium 133 is used in the most accurate atomic clocks. It serves as the primary standard for the SI definition of a second. This is based on the time interval taken to complete 9,192,631,770 atomic oscillations. The NPL CsFP2 caesium fountain clock in the UK is the world's most accurate measure of time. The atomic wrist watch was invented in 1949, and needs no winding. It keeps accurate time by being connected through radio waves to the atomic clock.

Sherlock was pacing in the mortuary. "Time of death, Molly; it's absolutely crucial." This was uttered in a growl. The detective was not in a good mood. He was tired, cold and hungry, running on nothing but adrenaline, coffee and nicotine patches for the past three days.

John watched him prowl like a caged animal. "Sherlock, ToD is never a simple mathematical equation. It's just too complicated- too many variables. If you push for an accuracy that is not possible, then you are putting Molly under intolerable pressure."

The long strides did not shorten. "Accuracy matters, John. Without it, we can't distinguish between the three suspects or, indeed, whether any of the three is a killer."

Molly Hopper tried to block out the noise of their discussion. She looked down at the slim figure of the teenager lying on the metal table. The photographs were done. The physical inspections, the temperature and rigor tests were over. She'd washed the body carefully, and the last red traces of dilute blood were now disappearing down the plughole at the end of the table. She slipped the shower head back into its clip, and stepped back to the body.

 _Tell me who did this to you and when. Give us a clue._  Molly's professionalism when she was alone with a body did not stop her from thinking about the person who had once inhabited the dead body. This was Alice Craddock, aged fourteen and a school girl at the Henrietta Barnet School in north London. Her body had been discovered in the undergrowth of Victoria Park, Finchley Central, showing obvious signs of sexual assault as well as a single knife wound to the side of her neck. She would have bled to death in a matter of minutes, and been unconscious very quickly. The Metropolitan Police believed she had been killed elsewhere, because there was so little blood at the scene of the crime.

Alice Craddock was the third victim in as many days. Cheryl Miller, fifteen, had been found in Alexandra Park, Muswell Hill, and the first, Susan Chambers, in Waterlow Park in Highgate. All three within three miles of each other. All three had been killed the same way. The newspaper headlines were calling them the "the park princess murders".

The ME on site had taken the girl's liver temperature and estimated that she had been dead no more than two hours when her body was found by a dog walker. But, it was a cold afternoon, below freezing for once in London, and that could hasten the rate of cooling. Add to that the fact that she was naked inside a plastic bin bag, and time of death would be challenging to pin down.

Because Alice had been found so quickly after her death, the police had rounded up three possible suspects. One was a previously convicted criminal with a record of domestic violence, who was seen walking back from the park to his flat on Ballards Lane. The second was a teenager known to be doing drugs which he had bought on the other side of the park; he was high as a kite, and violent when arrested. The third was a dishwasher in a local Indian restaurant, who was late getting to work, and had not given his employer an excuse. He always walked to work across the park. Each one of the three men was big enough to have carried the slender teenager some distance in the black bin liner in which her body had been found. None of them had a watertight alibi for being in the area.

Earlier that afternoon, Sherlock listened into the interrogations of the three men, and plotted a time-line. In each case there was between ten and fifteen minutes of their time that was unaccounted for, where there was no corroborating witness to strengthen their alibis.

"I'm sorry Sherlock. I just can't be more specific. Time of death is between two and four pm- even that is dropping the usual contingency I put in when we don't know the actual place where she was killed. It might have been a lot warmer than where she was dumped, and we don't know how long she was there. It's the best I can do." The pathologist looked apologetic.

Without a word Sherlock turned and left the mortuary, slamming through the swing doors, leaving John to apologise for his abrupt departure. by the time John caught up to the brunet, he was halfway to Newgate Street where they hailed a cab. When John started to speak in the taxi, Sherlock just ignored him and sat with his eyes closed. Back at Baker Street, Sherlock lay on the couch with his eyes closed and his hands steepled. John fixed himself some soup, but the bowl he left on the coffee table for Sherlock went cold, untouched. The doctor sighed, watched crap telly for a while,and then switched over to the BBC a few minutes before the ten o'clock news. The usual programme intro counted down the seconds to ten pm.

Sherlock suddenly sat up and grabbed his phone.

"Lestrade, do you still have the suspects in custody?" The answer must have been yes, because Sherlock carried on, "Then find their personal affects handed over when they were taken in. Compare their watches. One of them has moved his by at least fifteen to twenty minutes. He's the killer. Come tell me when you've sorted it."

Lestrade showed up at Baker Street just before midnight. "You were right, Sherlock, although how the hell you figured it out, I don't know. There were three watches, and none of them was wholly accurate. The guy who worked at the Indian restaurant had one of those atomic watches- you know, supposed to be accurate as hell, but it was twenty minutes slow. Turned out to be a Chinese fake and he could alter the time on it. He swore he didn't know, but when we investigated the restaurant, we found the blood traces on a knife that he'd not had time to clean up. He killed her in the kitchen, then mopped the floor so no one knew, and took out her body in the bin bag to the park. When the cook showed up, the place looked clean as a whistle. When the dishwasher came back in, the cook just assumed he had just arrived and was late. So, case closed- all due to a watch."

John looked down at the consulting detective, still lying prone on the sofa. "Not bad for someone who doesn't even know what day of the week it is." Sherlock smirked. "Time flies when I'm having fun."

oOo

Mycroft slid the leather strap into the buckle and tightened it around his brother's bony wrist. "It's special Sherlock, so don't lose it. You don't have to remember to wind it. The watch gets a radio signal from the atomic clock, so it's always accurate. So, no more excuses for being unpunctual. You can't pretend that the watch stopped or that it's slow. Because it's atomic it only loses a tenth of second every million years. Promise me that you will keep an eye on it, so you know what time it is."

Sherlock looked down at the clock face. "Atomic? How does that work?" His eyes were like saucers in wonder.

"Look it up yourself." Chemistry wasn't Mycroft's first love, not even his tenth when it came to academic subjects. But he knew his little brother's fascination was intense and he hoped that it would mean he'd take better care of this watch. And, more important, that he would use it to learn to keep to an agreed timetable.

They'd been home two weeks. At first, Sherlock was tentative around the house, as if afraid of the strange combination of both familiar and yet strange surroundings. For the first three days it was hard to get him to leave his room at all. Mycroft could understand the feeling, because it was odd for him, too. The house was the same, of course, and the staff, too- but with both Mummy and Father missing, it felt empty. The older boy kept expecting to hear his mother calling him, or to smell the scent of his father's cigarette smoke near the library or his office. For a ten year old who'd spent the last five and a half months confined to a hospital bed, the idea of having the freedom to roam the house must have been disconcerting.

Yesterday, Sherlock went missing. He didn't show up for dinner, and then Mycroft realised that no one had seen the boy since lunchtime. A frantic search with the housekeeper, Mrs Walters, yielded nothing. Mycroft and the gamekeeper, Frank Wallace, then tackled the grounds. With sixty acres of land to search, he knew it would be hard. Most of the staff working in the house and the farms went home by five, so there weren't many people he could rope into a thorough search. Calling them back, or worse, calling the local constabulary would be difficult to explain if Sherlock had just wandered off. He could just hear his Father's ridicule. "I told you Mycroft; he has to be institutionalised because he can't be trusted."

He tried to keep his anxiety under control. Mummy had believed that as a boy Mycroft needed the freedom to roam and had to learn the responsibility that came with it. Some might argue with that view in today's world of over-protective parents, but Mycroft had benefitted from it. She'd not allowed Sherlock that same freedom, because his autism made him more vulnerable. But Mycroft had played hide-and-seek with Sherlock since he was a toddler in the gardens closer to the house. When he'd deduced his brother's hiding place, he was often greeted with a smirking "Took you long enough." Every year, his brother became more and more adventurous and ingenious in his hiding places.

In Mummy's last summer, she didn't know that the nine year old had taken to sneaking out at night to explore on his own. Mycroft did not betray his secret, once he'd been sure that he wasn't at risk. He'd followed him a few nights just to be sure. "Just be sure to be back before sunrise, Sherlock; you know it will worry Mummy if she can't find you." But that was before Mummy died, before Sherlock's breakdown, before he ended up hospitalised for nearly six months- and before Mycroft had assumed responsibility for his brother's well-being. All those things now made it very hard for him not to feel every second of Sherlock's absence now as some kind of accusation of his own negligence.

Wallace had taken one of the estate's two Landrovers over to the far side of the paddocks and the farms. Mycroft was in the other one, driving through the woods and the pond. He'd learned to drive in this Landrover, and on a different occasion would have enjoyed the opportunity to do it again. Now, however, the windows were rolled down and he was getting hoarse from calling Sherlock's name.

Eventually, as the long sunlit evening turned to dusk, Mycroft spotted Sherlock beyond the deer park at the edge of the woods, sitting with his back up against a tree. He was sound asleep when Mycroft got to him, and clearly had not heard the vehicle or the calls. Relief warred with irritation. On the one hand, that fact that his brother felt able to explore on his own was reassuring; on the other, Mycroft was terrified that something might have happened to him while he was on his own. And to be gone for more than six hours was….too difficult to bear. For the first time in his life, he began to really understand why his mother was so protective of Sherlock.

Still, he held his own anger in check when he squatted down beside the sleeping boy. "Sherlock, wake up. Do you have any idea what time it is?"

The blue eyes that opened looked somewhat dazed for a few seconds, then took in the angle of the setting sun. "Oh, it must be…about 6.30? I don't know for sure; I haven't found my watch since we got back here."

"Sherlock, it's past nine o'clock. It's the longest day next week, when it won't be dark until after ten. You've been out of the house for six and a half hours. You've missed supper, not heard us when we were calling. You've scared the staff half to death."

That provoked a smirk. "But not you."

Mycroft decided that his relief outweighed his irritation, but his brother had to learn. He sighed. "No, I'm just  _cross_  with you. If you want the freedom to roam, then you have to keep an eye on the time. I'll get you a watch tomorrow, if you promise you'll keep to our agreement. You show up for lunch and dinner and you tell either me, Mrs Walters or Wallace about where you are planning to go. Those are the rules and you will have to abide by them. Promise?"

The ten year old looked up at his brother and nodded.

"Ok, let's go home."


End file.
